Large magnets are generally used for the separation of magnetic impurities from an aqueous slurry material, such as a dispersion of crude kaolin clay in water. Typically, these magnets comprise a large central canister containing a magnetically conductive matrix structure. The canister is placed in the center of a large magnet structure, such as a soft steel magnetic conducting core. Water cooled copper coils surround the canister to generate a high magnetic field, e.g., 20 kilogauss, within the matrix structure. Once the magnetic field is present, a slurry containing magnetic and nonmagnetic particles is run through the canister. The matrix structure collects the magnetic particles and the nonmagnetic particles exit the canister, where they are collected and discharged through an outlet manifold.
A significant drawback with existing magnetic separators is that the magnetically conductive matrix structure quickly becomes saturated with magnetic particles (typically after only about 10-15 minutes). When this occurs, flow of the product must be terminated and the magnetic field reduced to zero. When the field reaches zero, the magnetic particles collected in the matrix structure are backwashed to a pool where they can be safely accumulated and discarded. The device must then be restarted by regenerating the large magnetic field required for separating the magnetic particles. The time required to decay the magnetic field, backwash the matrix structure and then regenerate the field reduces the efficiency of the magnetic separator and increases the overall cost of the operation.
Unfortunately, the above described problem of saturation of the matrix element has been magnified by conventional methods of directing the flow of slurry through the magnetic separator. Typically, slurry is pumped through an inlet manifold and distributed to a number of individual pipes, which pass through the canister at individual conduits. The slurry then flows through the matrix structure and is discharged into a number of outlet pipes at the opposite end of the canister. One problem with this system is that the slurry generally passes directly through the matrix structure from inlet pipe to outlet pipe, thereby only coming into contact with localized portions of the matrix structure. These localized portions become quickly saturated, which reduces the period of time that the magnet is on line and capable of separating magnetic impurities from the product.